Question About F6F Hellcat Flaps

I'm building a 3D model of the F6F Hellcat to be flown in the X-Plane flight-sim environment.

Currently, I'm working on the flaps. Mainly due to the excellent article by Jim MacDonald titled Those Hellcat Flaps, I have a pretty good idea how they work. But one thing puzzles me: the small triangular shape on the upper wing surface between the inner and outer flap.

Below is a screen-grab of a page of photos and notes I put together as I tried to decide exactly what that triangle is and what purpose it serves. At first I thought the triangular shape was part of the inner flap. But further study of photos (as shown below), made me question that theory.

Does the triangle have something to do with the fact that the wing-fold is at that point?